One technique for producing electrical energy from wind is to build a “wind farm” that consists of a number of wind turbines located at various fixed positions. In an example, each wind turbine has a rotor that is attached to multiple blades. These blades transform energy in the wind impinging on the blades into a rotational torque to drive an electrical generator and thus produce electricity. The rotor, electrical generator, and other components, are typically located within a housing, or nacelle, that is positioned on top of a tower or other vertical support. The rotor generally protrudes from this housing to allow the blades attached to the rotor to rotate as the wind impinges upon them.
In general, wind is able to arrive from any direction at a wind turbine. In order to effectively operate with wind arriving from different directions, the housing of the wind turbine is able to change the direction in which the rotor faces. The rotor is generally substantially perpendicular to a plane of the blades attached to that rotor. The direction of the rotor is referred to as “yaw.” The yaw of a wind turbine and is generally expressed as an angle relative to some reference direction, such as north.
In an example, each wind turbine has a yaw controller that maintains the yaw of the wind turbine such that the rotor faces the direction of the presently observed wind, which is to say that the plane of the blades attached to the rotor is perpendicular to the present direction of the wind. In various examples, wind measurement equipment measure wind direction and speed at various locations around the wind farm. These wind measurements are provided to the yaw controller to allow the yaw controller to keep the wind turbine facing the oncoming wind.